bringing light to life
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Bringing light to life
March 2012
Najmi KamalPower Design Engineer for Lighting
TI Lighting System Solution
• NSC + TI = strong system level know-how
4
Lighting Portfolio LED driver Architecture Dimming techniques
LED driverMR16 LED bulb designController, Ref design
High brightness LEDs driverOff line LED Bulb/T8 Ref design
Multi Channel LED driverSystem solutions ( Triac, DALI, 0 to 10V)
WEBENCH Architect
Lighting Summary
6
Texas Instrument’s Current LED Driver Solutions
Quick Selection guide
How to drive LEDs?
• With current (high end system)– Light output is proportional to forward current– Brightness AND color can change with current
• With power(low end system)– Bulb
N or P FET
Duty Cycle Limits Max VO in Bucks
High Side N-MOSFETs (internal or external FETs)
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Must turn off for ~200 ns each cycle to recharge CBOOT
The max number of LEDs is then:
The lower the switching frequency, fSW, the closer VO-MAX is to VIN
PFET Bucks Can Provide 100% Duty Cycle
• High Side P-MOSFETs
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Gate is driven below source to turn the PFET ON
Gate can drive to VCC indefinitely
PFET can stay on indefinitely
True 100% duty cycle capability
Buck is better than buck-boost
Better efficiency
Less parts
Faster dimming
Dimming
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Various dimming techniques
• Dimming using PWM signal
– White LEDs change Colour over Current!
– Solution:
Maintain Current and Change ON-Time = PWM
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Two different PWM dimming methods
• First method: Dim 1: Continuous inductor current (Good EMC, extra Mosfet )
• Second method: Dim 2: more efficient (2khz dim max)
D0LED0
D1LED1
D3LED2
Q2NMOS
Q1NMOS
Vout
GND
PWM dim1
PWM dim2
Output capacitor for a Buck topology
+
-
+
L
C OVIN
D
Δ I L
V FB
V F
+
-
+
-
R FB
Δ I C
I o
Vo
Vo Limited by VIN
Cout not needed
Continuous output current, low EMI
Easy to stabilize, if needed
Inherent protections against
failure
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Buck (step-down) DCM or CCM
LED Drivers
LM3409/09HV: High-Side PFET Buck Controller
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– VIN 6V to 42V (LM3409)
– VIN 6V to 75V (LM3409HV)
– External power PFET
• 100% Duty Cycle Capable
• Output Currents up to 4A
– Differential, high-side current sense
• Simplifies system wiring
– PWM dimming and analog dimming at 1000:1
– Thermally enhanced eMSOP-10 package
– No control-loop compensation
IADJ
EN
CSN
LM3409/09HV
UVLO
D1
L1
RSNS
CIN
VIN
IF up to 4A
VCC
COFF
GND Q1
CSP
CF
VIN
ROFF
PGATEVO
VO
COFF
RUV2
RUV1
DAP
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LM3401 Hysteretic PFET controller HB LED Driver
Key Features
• VIN Range: 4.5V – 35V
• Output range: 0.2V (Vfb) to VIN, adjusts to deliver constant current to up to 9 HB LEDs in series with scalable LED current > 2A
• No output cap, no compensation components
• Logic level dimming 1% to 100%, 70nS delay
• Controlled start up allows PWM at Vin for dimming
• PFET driver 100% duty cycle capable
• Adjustable Dual Side Hysteresis
– Adjustable ripple current
– Flexible inductor selection
– Fine tuning of switching frequency up to 1.5MHz
• MSOP-8 package
Applications:Automotive Lighting, General Illumination, MR16
replacement, Industrial Lighting, Gaming, High-end LCD Backlighting
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• Runs from 6V to 35V• Drives one white LED in at 800 mA• High-side PFET topology can do 100% duty cycle
Ref design: LM3401 - 20 Cent-Sized PCB
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Key Features: COT• VIN Range:
– LM340X: 6V – 42V, Buck– LM340XHV: 6V – 75V, Buck
• True average current control• Two PWM LED dimming options:
– Fast logic pin PWM dimming– LM3406: 2-wire dimming by VIN pin-
70%• Feedback Voltage = 200mV• Internal NFET for reduced parts count• Switching Frequency up to 1MHz • Exposed pad eTSSOP-14 package• Drives 1W, 3W, and higher powered LEDs
LM3402/4/6 and LM3402HV/4HV/6HV 0.5A/1.0A/1.5A HB LED Driver
GND
DIM
BOOT SW
VOUT
RON
LM3406/06HV
VIN
D1
L1CB
RSNS
CF
RONCIN
VIN
IF
VCC
CS
COMP
CC
GND
BOOT SW
VOUT
RON
VIN
D2
L1CB
RSNS
CF
RONCIN
VIN
IF
VCC
CS
COMP
CC
VINS
D1
LM3406/06HV
Fast PWM Dim
2-Wire Dim
Applications:Automotive Lighting, General Illumination, Industrial
Lighting, Arcitectual
• Support LED power up to 60W*: 18x 3W HBLEDs • Patented True Average Current Control Provides ±3% Accuracy to Average LED Current• Requires NO external current sensing resistor • Up to 96% efficiency ,1 active component• High contrast ratio
– (Minimum dimming current pulse width <10 µS)
• Adjustable Constant LED current from 350mA to 1000mA
– ±3% LED current accuracy
• Support PWM /analog dimming and thermal fold-back
• Wide input voltage range:– 4.5V to 42V (LM3414)– 4.5V to 65V (LM3414HV)
• Constant Switching Frequency – adjustable from 250 kHz to 1000 kHz
• Thermal shutdown protection• ePSOP-8 or LLP-8 package
LM3414/14HV Low Side Converter for High Power LED Drives
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VIN
LX
DIM
FS
PGND
IADJ
GND
VCC
* DAP connect to GND
D1
LED
x 4
L1
GND
Iout = 500mA (nom.)
LM3414
RFS
RIADJ
Vin
GND
24VDCnom
CIN
CVCC
GND
GND
40V3A
68uH
X7R 50V4.7uF
X7R16V 1uF
5.76k40.2k
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TPS92550 (LML416504)LED Driver Module
• Wide Input Voltage Range : 4.5V - 65V • Can drive up to 18 LEDs in series with 65V input • LED current accurately trimmed to +/-3% • 450mA LED current + fine tuning by external resistor (=
analog dimming!)• Integrated shielded inductor and power components • Efficiency up to 95% • Input Under-Voltage Lock-Out (UVLO) • Stable with ceramic and low ESR capacitors • Low radiated and conducted emissions • LED open and short circuit protection • Thermal Shutdown • Only 3 external passive components needed• Simple PCB layout and high Power Density • RoHS Compliant
Actual LML416504 Module
Retrofit MR16
AC Transformer for MR16 Reference Designs
Issue:•Resistive load = PF•Doesn’t switch off at 0v input•Small form factor
PHASE DIMMERAC
MAINS
12VACRMS
TRANSFORMER
MR16 MR16 MR16
LED MR16 Replacement Solutions
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LM3407 0.35A HB LED Driver
Key Features: floating buck
• VIN Range: 4.5V to 30V
• Less than ±10% load current variation• Adjustable switching frequency from
150 kHz to 1 MHz• Internal low side NFET for reduced parts
count• Feedback Voltage = 200mV• Fast PWM dimming enabled• Exposed pad eMSOP-8 package• Drives 1W LEDs
Applications:Automotive Lighting, General Illumination, Industrial
Lighting
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• Runs from low voltage: 11VAC to 20VAC or 14V to 30VDC
– Magnetic transformers only– Nominal 12VAC or 24VDC inputs
• Drive three white LEDs in series at 350 mA ±10%
• 1 MHz switching frequency for minimum inductor size
• Low-side buck topology uses small, efficient N-MOSFET
• Complete solution including a diode bridge and holdup capacitor fits in standard MR-16 bulb housing
LM3407 - MR-16 Retrofit
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Halogen MR16 vs. SSL MR16 waveforms
Final schematic of the MR16
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• Vin: 12VAC• Vout: 6.2V (2 series LEDs)• Iout: 1A • Pout: 6.2W• Efficiency: 81%• PF: 0.85• Dimmable with electronic low
voltage dimmers/electronic transformers
• LED Agnostic • Demo board, reference design,
CAD design files available online (RD-188)
LM3401 MR16 Reference Design
http://www.national.com/rd/RDhtml/RD-188.html
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TPS40211 Sepic Reference Design
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LM3444 Boost Reference Design
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LM3444 BUCK BOOST Reference Design
Controller/ Regulator/ Ref design
Why Not More Internal FET Boosts?
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Output Current with Ripple (ΔiF)
Inductor Current with Ripple (ΔiL)
O
INOLIMITMAXF V
VVII 1
OIN
OLIMITMAXF VV
VII 1
Boost and Buck-boost
SEPIC and Flyback
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LM3410 Boost and SEPIC LED Driver
FB
Vin SW
2
1
3
5
4DIM
Vin
1R
1C
1D1L
2CDIMM
GND
Key Features
– Input voltage range of 2.75 to 5.5V
– Output voltage range of 3 to 24V
– Switch current up to 2.1A guaranteed over temperature
– Low, 190mV feedback voltage
– Option of 520 or 1600 kHz switching frequency
– PWM Dim pin
– 160mΩ switch resistance
– Current Mode control with internal compensation
Applications:Portable Illumination/Flashlight, Personal Navigation
Device, Portable Measurement Equipment, Automotive Control/Entertainment Console, Portable DVD Player
eMSOP-8 SOT23-5LLP-6
TPS615003A, Boost High Brightness LED DriverFeatures Benefits• Operating Voltage Ranges:
• VIN: 2.9-18V• VOUT: VIN to 38V
• Suitable for Use in Battery,12V, or 15V Systems
• 3A Peak Switch Current • Can be Used to Drive High Current LEDs• Adjustable Switching Frequency: 200k-2.2MHz with up
to 93% Efficiency• Allows Designed to be Optimized for Efficiency or Size
• Dimming: PWM or PWM-to-Analog • Use PWM for No LED Color Shift. Use Analog to Eliminate Audible Noise from Pulsed Currents.
• UVLO, Over-Voltage, Current Limit and Thermal Shutdown
• Protects Against Abnormal and Fault Conditions
Applications• LED General Illumination• LED Flashlights• LED Backlighting
TOOLS
•TPS61500EVM-369
LM3429: Low Side N-MOSFET Controller for Constant Current LED Drivers
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LM342x Controls the Floating Buck-Boost
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VIN
VCC
RCT
EN
NDIM
CSH
COMP
AGND RPD
OVP
IS
GATE
PGND
HSP
HSN
DDRV
PWM DIMSIGNAL
VO
VO
VIN = 4.5V to 75V
LM
3421
IF
RSNSCO
D1
Q1
L1
CIN
VO controlled with respect to VIN
Linear IF control
Adjustable, precision threshold protection for LEDs that fail open-circuit
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LM3423: Adds Fault Flag, Powergood Flag, and Input Disconnect
– FLT pin is for error signaling or for input disconnect via PFET
– TIMR sets the delay between when LED current is out of spec and when FLT flag goes logic HIGH
– DPOL selects the polarity of the nDIM pin when PWM dimming
– LRDY is a powergood pin for signaling a system microprocessor
VIN
RCT
VCC
EN
NDIM
CSH
COMP
AGND RPD
OVP
IS
GATE
PGND
HSP
HSN
DDRV
VO
VO
VIN = 4.5V to 75V
LM
3423
IF
RSENSE
CO
D1
QSW
L1
CIN
ON/OFF
CBYP
RCSH
CCOMP
RHSP
RHSN
RT
CT
ROV2ROV1
+VSENSE
_
RUV2
RUV1
+VLEDS
-
QDIM
FLT
DPOL
LRDY
5V
To system microcontroller
TIMR
CTIMR
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- DC Input Voltage 12V to 30V- SEPIC circuit bucks or boosts as needed
• ILED up to 1.5A
• 6 White and one yellow LED for CCT adjustment
– All LEDs in series– Yellow LED has separate shunt NFET
dimming– 250Hz PWM dimming
• LM26675 supplies 5V for Nuventix SynJet active cooling
• 1500 lumens at 50 lm/W
Ref design: LM3429 PAR-38 Spotlight
5757
PAR-38 Spot Light – Block Diagram
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- DC Input Voltage 9V to 36V- Buck-boost circuit runs from 12VDC or
24VDC rails
• ILED up to 1A
• Powers 1 to 12 LEDs in series• Accepts standard 0-10V linear dimming
signals and adjusts LED current down to zero
• LM2842 supplies 5V for Nuventix SynJet active cooling
Ref Design:LM3429 MR-16 retrofit with active cooling
LM3429 MR-16 Buck-boost Schematic
LED Offline products
•Retrofit E27
•T8 tube non retrofit
•High power bay (multi string)
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